1. Field of the Invention
The present invention relates to a control device for a synchromesh automatic transmission, by which a gear can be securely changed to an aimed gear position.
2. Discussion of Background
As a control device for a synchromesh automatic transmission, used for vehicles, is disclosed in, for example, Japanese Unexamined Patent Publication JP-A-63-270252. A technique disclosed therein is that a combustion engine and a synchromesh automatic transmission are coupled through an electromagnetic clutch; a throttle opening degree is controlled so as to maintain a degree of change between a rotational speed of the combustion engine at time of releasing the electromagnetic clutch and a rotational speed of the combustion engine at time of recoupling the electromagnetic clutch upon switching of transmission gears within a predetermined range; and a control input is corrected by a learning routine, conducted by each gear changing operation to deal with scattering and various conditions of the combustion engine, whereby a shock, caused at time of changing the gears, is relaxed.
In a shifting device, changing the gear of the transmission, according to the conventional technique, a pair of three-position oil pressure cylinders, controlling a shifting and selecting lever respectively in an axial direction and a rotational direction is used. By actuating the three-position oil pressure cylinder for selecting, shift rods are selected, and by actuating the three-position oil pressure cylinder for shifting, the selected shift rod is moved to switch a gear position. Other than the shifting device of the oil pressure type, an electromotive synchromesh automatic transmission for actuating the shifting and selecting operations using two motors is also generally used. In such an electromotive synchromesh automatic transmission, a gear position is switched such that a sleeve gear to be operated is selected by a selecting motor controlling a position by a selecting position sensor, and the sleeve gear is moved to be engaged with an aimed gear by the shifting motor controlling a shifting position by a shifting position sensor.
However, in this synchromesh automatic transmission, a control unit, receiving a feed-back from the position sensors, controls the shifting position and a selecting position. Therefore, when the control unit or a system is erroneously operated to cause a situation that the aimed gear is not engaged and the electromagnetic clutch is coupled in a state that a gear different from the aimed gear is engaged, a shock occurs by an abrupt engine brake caused by an erroneous gear change, knocking of the engine occurs by an insufficient acceleration, or a traffic accident may be caused by an operation erroneously selecting forward gear positions and a backward gear position in an extreme case.
It is an object of the present invention to solve the above-mentioned problems inherent in the conventional technique and to provide a control device for a synchromesh automatic transmission, which can be stably operated without erroneous operations.
According to a first aspect of the present invention, there is provided a control device for a synchromesh automatic transmission comprising:
an input shaft coupled to a crank shaft of a combustion engine through a clutch mechanism;
an output shaft coupled to the input shaft by gears;
a plurality of groups of transmission gears, having different gear ratios and interposed between the input shaft and the output shaft;
a coupling mechanism selectively coupling one of the plurality of groups of the transmission gears with the output shaft;
a shifting and selecting actuator operating the coupling mechanism in shifting and selecting directions;
a shifting position sensor detecting a control input in the shifting direction by the shifting and selecting actuator;
a selecting position sensor detecting a control input in the selecting direction by the shifting and selecting actuator; and
a control unit instructing an operation to the shifting and selecting actuator,
wherein the control unit detects a position of completing the operation from outputs from the shifting and selecting position sensors after finishing a gear changing operation, and judges whether or not the position of completing the operation is within a range of target position in order to finish the operation.
According to a second aspect of the present invention, there is provided a control device for a synchromesh automatic transmission comprising:
an input shaft coupled to a crank shaft of a combustion engine through a clutch mechanism;
an output shaft coupled to the input shaft by gears;
a plurality of groups of transmission gears having different gear ratios and interposed between the input shaft and the output shaft;
a coupling mechanism selectively coupling one of the plurality of groups of the transmission gears with the output shaft;
a shifting and selecting actuator operating the coupling mechanism in shifting and selecting directions;
an input shaft rotational speed sensor detecting a rotational speed of the input shaft;
an output shaft rotational speed sensor detecting a rotational speed of the output shaft; and
a control unit instructing an operation to the shifting and selecting actuator,
wherein the control unit calculates a target ratio of rotational speeds of the input shaft and the output shaft from a gear ratio of transmission gears, which are newly engaged after finishing a gear changing operation, judges whether or not the rotational speed ratio obtained from outputs of the input shaft rotational speed sensor and the output shaft rotational speed sensor is within the target rotational speed ratio, and makes the operation complete.
According to a third aspect of the present invention, there is provided a control device for a synchromesh automatic transmission comprising:
an input shaft coupled to a crankshaft of a combustion engine through a clutch mechanism;
an output shaft coupled to the input shaft by gears;
a plurality of groups of transmission gears having different gear ratios and interposed between the input shaft and the output shaft, and one of the groups of the transmission gears is for a reverse driving;
a coupling mechanism selectively coupling one of the plurality of groups of the transmission gears with the output shaft;
a shifting and selecting actuator operating the coupling mechanism in shifting and selecting directions;
a reverse driving detecting means detecting an incident that the coupling mechanism is coupled with transmission gears for the reverse driving;
a control unit instructing an operation to the shifting and selecting actuator; and
a shifting lever, through which an operator transmits operating conditions to the control unit,
wherein the control unit compares an instruction signal by the shifting lever with a detecting signal from the reverse driving detecting means after finishing a gear changing operation, and judges whether or not the instruction signal and the detecting signal match, and finishes the operation.
According to a fourth aspect of the present invention, there is provided the control device for the synchromesh automatic transmission,
wherein when the control unit judges that the position of completing the operation is not within the range of target position, the gear changing operation is repeated.
According to a fifth aspect of the present invention, there is provided the control device for the synchromesh automatic transmission,
wherein when the control unit judges that the rotational speed ratio is not within the range of the target rotational speed ratio, the gear changing operation is repeated.
According to a sixth aspect of the present invention, there is provided the control device for the synchromesh automatic transmission,
wherein when the control unit judges that the instruction signal from the shifting lever does not match the detecting signal from the reverse driving detecting means, the gear changing operation is repeated.